At a time when policymakers have made reducing unintended pregnancies a national priority, 33 states have made it more difficult or more expensive for poor women and teenagers to obtain contraceptives and related medical services, according to an analysis released yesterday by the nonpartisan Guttmacher Institute.

From 1994 to 2001, many states cut funds for family planning, enacted laws restricting access to birth control and placed tight controls on sex education, said the institute, a privately funded research group that focuses on sexual health and family issues.

The statewide trends help explain why more than half of the 6 million pregnancies in the United States each year are unintended and offer clues for tackling problems associated with teenage pregnancy and abortion, said researchers who specialize in the field.

"The most powerful and least divisive way to decrease abortion is to reduce unintended pregnancy," said Sarah Brown, director of the nonpartisan National Campaign to Prevent Teen Pregnancy. "If we can make progress reducing unintended pregnancy, we can make enormous progress reducing abortion."

The report, the first to measure the impact of state actions on reproductive health care, is based on a comprehensive census by the institute using the most recent available data. Advocates involved in the intense political debate over abortion were reluctant to comment on the findings, but experts on women's health and family planning praised Guttmacher for offering an agenda both sides could support.

"Whether you're pro-choice or pro-life, everyone ought to agree that preventing unintended pregnancies is a good thing to do," said Isabel Sawhill, a senior fellow at the Brookings Institution. Sawhill, whose research is cited by both conservative and liberal groups, said other factors contribute to unintended pregnancies, including miscommunication between partners, insufficient knowledge about contraceptives and an "it will never happen to me" attitude.

Despite some gains, the United States still lags far behind most industrialized nations in reducing abortion and teenage pregnancy. In 2002, 21 in 1,000 American women age 15 to 44 had an abortion. Although that is the lowest abortion rate since 1974, the decline has stalled, prompting fears that individuals and policymakers have lost focus on the underlying problem of unintended pregnancies, said Guttmacher President Sharon L. Camp.

"Unintended pregnancy in the United States is twice as high as in most of Western Europe," she said in an interview. "As a direct result, abortion rates are twice or three times as high as European countries. There is no reason why abortion rates need to be as high as they are."

The problem is particularly acute for the nation's estimated 17 million adolescent girls and low-income women, because a lack of education and money are often barriers to practicing abstinence or effective birth control.

In 2000, federal health officials set a goal of reducing unintended pregnancies by 40 percent within 10 years. States, through legislative and budgetary decisions, can be major players in that effort, Camp said. California and a few other states have leveraged federal Medicaid money to extend family-planning services to more poor women. For every dime the state puts in, the federal government pays 90 cents.

"This is really a smart move for states to make," Camp said. Yet for every state that has invested in reproductive health care or passed laws permitting pharmacists to dispense emergency contraception without a prescription, Guttmacher found at least another state that moved in the opposite direction.

"It's not only that at least half of the states are not doing many things they could do to reduce unintended pregnancy -- some are making contraception less easy for women and men," Camp said.

The Guttmacher rankings belie conventional political wisdom. California, New York, South Carolina and Alabama have made the greatest strides in helping low-income women receive health care and contraception, despite the fact that the two coastal states are considered "blue" states that lean to the left politically, while the two southern states are deemed "red" for their conservative tilt.

At the same time, states as different as Nebraska, Ohio and Utah were among the worst when it came to providing access to contraceptives for needy women and teenagers, as well as gynecological exams and information on preventing pregnancy and sexually transmitted diseases.

States have an incentive for investing in reproductive services, Camp said. Every $1 spent on family planning saves $3 in health care costs related to a pregnancy.

The Guttmacher Institute was founded in 1968 as a "semiautonomous division of Planned Parenthood Federation of America" but now operates independently, according to its Web site. The report and state data can be read at http://www.agi-usa.org/ .